The tetrafluoropropene compound HFO-1234ze, is a useful compound with low global warming potential. HFO-1234ze is useful in numerous applications including as a foam blowing agent, refrigerant, and as monomer for homopolymers and copolymers.
Several methods are known for the preparation of HFO-1234ze. For example, U.S. Pat. No. 6,548,719 describes the production of many fluoro-olefins including CF3CH═CHF from CF3CH2CF2H (245fa) by dehydrohalogenation in the presence of a phase transfer catalyst. U.S. Pat. Nos. 5,986,151 and 6,124,510 describe the gas phase catalytic dehydrofluorination of CF3CH2CF2H to afford CF3CH═CHF. These documents are hereby incorporated herein by reference.
Gas phase dehydrochlorination of CF3CH2CHFCl (244fa) is reported to give CF3CH═CHF as described in U.S. Pat. No. 7,829,748. Vapor phase fluorination of CF3CH═CHCl (1233zd) with HF and SbF5 catalyst affords HFO-1234ze along with 245fa and CHClF—CF2—CF3. See, for example, U.S. Pat. No. 7,829,748. This document is hereby incorporated herein by reference.
The main disadvantages of the above described methods are that in each case the starting materials, for example CF3CH2CF2H, typically need to be made by multiple reaction steps, and/or with relatively expensive raw materials, and thus there is a need to provide an improved process for the production of HFO-1234ze, at least from a cost effectiveness viewpoint.
Accordingly, the present invention has been developed, namely a process which utilizes relatively inexpensive and commercially available starting materials for making HFO-1234ze as detailed below.